Television station

This article is about a television transmitting location or company. For the technical concept related to broadcast frequencies, seeTelevision channel.For the concept of a specific television service (known as a "channel" or "station" in some areas), seeTelevision network.

Atelevision stationis a set of equipment managed by a business, organisation or other entity such as anamateur television(ATV) operator, that transmits video content and audio content viaradio wavesdirectly from atransmitteron the earth's surface to any number of tunedreceiverssimultaneously.

Overview

TheFernsehsender Paul Nipkow(TV Station Paul Nipkow) inBerlin,Germany,was the first regular television service in the world.It was on the air from 22 March 1935, until it was shut down in 1944. The station was named afterPaul Gottlieb Nipkow,the inventor of theNipkow disk. Most often the term "television station" refers to a station which broadcasts structured content to an audience or it refers to the organization that operates the station. Aterrestrial televisiontransmission can occur viaanalog televisionsignals or, more recently, viadigital televisionsignals. Television stations are differentiated fromcable televisionor other video providers as their content is broadcast via terrestrial radio waves. A group of television stations with common ownership or affiliation are known as aTV networkand an individual station within the network is referred to asO&Ooraffiliate,respectively.

Because television station signals use the electromagnetic spectrum, which in the past has been a common, scarce resource, governments often claim authority to regulate them.Broadcast television systemsstandards vary around the world. Television stations broadcasting over an analog system were typically limited to onetelevision channel,but digital television enables broadcasting viasubchannelsas well. Television stations usually require abroadcast licensefrom agovernment agencywhich sets the requirements and limitations on the station. In the United States, for example, atelevision licensedefines thebroadcast range,or geographic area, that the station is limited to,allocates the broadcast frequencyof theradio spectrumfor that station's transmissions, sets limits on what types oftelevision programscan beprogrammedfor broadcast and requires a station to broadcast a minimum amount of certain programs types, such aspublic affairs messages.

Another form of television station isnon-commercial educational(NCE) and consideredpublic broadcasting.To avoidconcentration of media ownershipof television stations, government regulations in most countries generally limit the ownership of television stations by television networks or other media operators, but these regulations vary considerably. Some countries have set up nationwide television networks, in which individual television stations act as mererepeatersof nationwideprograms.In those countries, the local television station has nostation identificationand, from a consumer's point of view, there is no practical distinction between a network and a station, with only small regional changes in programming, such as localtelevision news.

Transmission

Cerro de Punta,Puerto Rico's highest peak, and its TV transmission towers

To broadcast its programs, a television station requiresoperatorsto operate equipment, a transmitter orradio antenna,which is often located at the highest point available in the transmission area, such as on asummit,the top of a highskyscraper,or on a tallradio tower.To get a signal from themaster controlroom to the transmitter, astudio/transmitter link(STL) is used. The link can be either by radio orT1/E1.Atransmitter/studio link(TSL) may also sendtelemetryback to the station, but this may beembeddedinsubcarriersof the main broadcast. Stations which retransmit or simulcast another may simply pick-up that stationover-the-air,or via STL or satellite. The license usually specifies which other station it is allowed to carry.

VHFstations often have very tall antennas due to their longwavelength,but require much lesseffective radiated power(ERP), and therefore use much lesstransmitter power output,also saving on theelectricitybilland emergencybackup generators.InNorth America,full-power stations onband I(channels 2 to 6) are generally limited to 100 kW analog video (VSB) and 10 kW analog audio (FM), or 45 kW digital (8VSB) ERP. Stations onband III(channels 7 to 13) can go up by 5dBto 316 kW video, 31.6 kW audio, or 160 kW digital. Low-VHF stations are often subject tolong-distance receptionjust as with FM. There are no stations onChannel 1.

UHF,by comparison, has a much shorter wavelength, and thus requires a shorter antenna, but also higher power. North American stations can go up to 5000 kW ERP for video and 500 kW audio, or 1000 kW digital. Low channels travel further than high ones at the same power, but UHF does not suffer from as muchelectromagnetic interferenceand background "noise" as VHF, making it much more desirable for TV. Despite this, in the U.S., theFederal Communications Commission(FCC) is taking another large portion of this band (channels 52 to 69) away, in contrast to the rest of the world, which has been taking VHF instead. This means that some stations left onVHFare harder to receive after theanalog shutdown.Since at least 1974, there are no stations onchannel 37in North America forradio astronomypurposes.

Program production

Most television stations arecommercial broadcastingenterprises which are structured in a variety of ways to generaterevenuefromtelevision commercials.They may be anindependent stationor part of abroadcasting network,or some other structure. They can produce some or all of their programs or buy somebroadcast syndicationprogramming for or all of it from other stations or independent production companies.

Many stations have some sort oftelevision studio,which on major-network stations is often used fornewscastsor otherlocal programming.There is usually anewsdepartment,wherejournalistsgather information. There is also a section whereelectronic news-gathering(ENG) operations are based, receivingremote broadcastsviaremote pickup unitorsatellite TV.Outside broadcastingvans,production trucks,orSUVswithelectronic field production(EFP) equipment are sent out withreporters,who may also bring back news stories onvideo taperather than sending them backlive.

To keep pace with technology United States television stations have been replacingoperatorswithbroadcast automationsystems to increase profits in recent years.

Some stations (known asrepeatersortranslators) onlysimulcastanother, usually the programmes seen on its owner'sflagshipstation, and have no television studio or production facilities of their own. This is common indeveloping countries.Low-power stations typically also fall into this category worldwide.

Most stations which are notsimulcastproduce their ownstation identifications.TV stations may alsoadvertiseon or provide weather (or news) services to localradio stations,particularly co-ownedsister stations.This may be abarterin some cases.

See also

• Class A television service
• Digital television transition
• Fernsehsender Paul Nipkow:the world's first regular television service
• Low-power broadcasting
• Must carry
• Pay television
• Significantly viewed out of market TV stations in the United States
• Terrestrial television
• List of European television stations
• List of North American broadcast station classes

External links

• Media related toTelevision channelsat Wikimedia Commons